Green Chemistry: Microwave Assisted Organometallic Reaction - PowerPoint PPT Presentation

Loading...

PPT – Green Chemistry: Microwave Assisted Organometallic Reaction PowerPoint presentation | free to download - id: 495008-NzhkM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Green Chemistry: Microwave Assisted Organometallic Reaction

Description:

Green Chemistry: Microwave Assisted Organometallic Reaction Green Chemistry To promote innovative chemical technologies that reduce or eliminate the use or generation ... – PowerPoint PPT presentation

Number of Views:640
Avg rating:3.0/5.0
Slides: 119
Provided by: teod4
Learn more at: http://www.unicam.it
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Green Chemistry: Microwave Assisted Organometallic Reaction


1
Green Chemistry Microwave Assisted
Organometallic Reaction
2
Green Chemistry
  • To promote innovative chemical technologies
    that reduce or eliminate the use or generation of
    hazardous substances in the design, manufacture,
    and use of chemical products.

3
What does the Chemical Industry do for us?
4
Green chemistry
  • is about
  • Waste Minimisation at Source
  • Use of Catalysts in place of Reagents
  • Using Non-Toxic Reagents
  • Use of Renewable Resources
  • Improved Atom Efficiency
  • Use of Solvent Free or Recyclable Environmentally
    Benign Solvent systems



5
Green Chemistry Responsibility
  • Why is there no Green Geology or Green
    Astronomy?
  • Because chemistry is the science that introduces
    new substances into the world and we have a
    responsibility for their impact in the world.
  • - Ronald Breslow

6
Green Chemistry is also called
  • A new approach to designing chemicals and
    chemical transformations that are beneficial for
    human health and the environment
  • An innovative way to design molecules and
    chemical transformations for sustainability
  • Meeting the needs of the current generation
    without compromising the ability of future
    generations to meet their own needs
  • Benign by design
  • Pollution prevention at the molecular level

7
What is Green Chemistry?
  • Green chemistry is the study of how to design
    chemical products and processes in ways that are
    sustainable and not harmful for humans and the
    environment.
  • Three components catalysis, solvents, non-toxic
  • 12 principles of green chemistry

8
Green Chemistry Is About...
Waste
Materials
Hazard
Reducing
Risk
Energy
Cost
9
Why do we need Green Chemistry ?
  • Chemistry is a very prominent part of our daily
    lives.
  • Chemical developments also bring new
    environmental problems and harmful unexpected
    side effects, which result in the need for
    greener chemical products.
  • A famous example is the pesticide DDT.

10
The 12 Principles of Green Chemistry (1-6)
11
The 12 Principles of Green Chemistry (7-12)
7 Use of Renewable Feedstocks A raw material or
feedstock should be renewable rather than
depleting whenever technically and economically
practicable. 8 Reduce Derivatives Unnecessary
derivatization (use of blocking groups,
protection/de-protection, and temporary
modification of physical/chemical processes)
should be minimised or avoided if possible,
because such steps require additional reagents
and can generate waste. 9 Catalysis Catalytic
reagents (as selective as possible) are superior
to stoichiometric reagents. 10 Design for
Degradation Chemical products should be designed
so that at the end of their function they break
down into innocuous degradation products and do
not persist in the environment. 11 Real-time
Analysis for Pollution Prevention Analytical
methodologies need to be further developed to
allow for real-time, in-process monitoring and
control prior to the formation of hazardous
substances. 12 Inherently Safer Chemistry for
Accident Prevention Substances and the form of a
substance used in a chemical process should be
chosen to minimise the potential for chemical
accidents, including releases, explosions, and
fires.
12
What is Green?
  • Sustainable
  • Kinder and gentler to people and the planet

13
Green Chemistry
14
The cost of using hazardous materials
15
Conventional Heating vs Alternative Energy Source
  • Conventional Heating
  • Bunsen burner
  • Oil bath
  • Heating mantle
  • Alternative Energy Sources
  • Microwave
  • Ultrasound
  • Sunlight / UV
  • Electonchemistry

16
Clean Chemical Synthesis Using Alternative
Reaction Methods
  • Alternative Energy Sources
  • Microwave
  • Ultrasound
  • Sunlight / UV
  • AlternativeReactionMedia/Solvent-free
  • Supercritical Fluids
  • Ionic Liquids
  • Water
  • Polyethylene glycol (PEG)
  • Solvent free

17
  • Microwaves in Synthesis

18
History or how it all began
  • While fire is now rarely used in synthetic
    chemistry, it was not until Robert Bunsen
    invented the burner in 1855 that the energy from
    this heat source could be applied
  • There is some controversy about the origins of
    the microwave power cavity called the magnetron
    the high-power generator of microwave power.
  • The British were particularly forward-looking in
    deploying radar for air defense with a system
    called Chain Home which began operation in 1937.
  • Originally operating at 22 MHz, frequencies
    increased to 55 MHz.
  • 1921 was published by A.W. Hull the earliest
    description of the magnetron, a diode with a
    cylindrical anode
  • 1940 It was developed practically by Randall and
    Booth at the University of Birmingham in England
    they verified their first microwave
    transmissions 500 W at 3 GHz.
  • A prototype was brought to the United States in
    September of that year to define an agreement
    whereby United States industrial capability would
    undertake the development of microwave radar.
  • 1940 the Radiation Laboratory was established at
    the Massachusetts Institute of Technology to
    exploit microwave radar. More than 40 types of
    tube would be produced, particularly in the
    S-band (i.e. 300 MHz). The growth of microwave
    radar is linked with Raytheon Company and P.L.
    Spencer who found the key to mass production.

19
History or how it all began
  • 1946 Dr. Percy Spencer-the magnetron inventor he
    has found a variety of technical applications in
    the chemical and related industries since the
    1950s, in particular in the food-processing,
    drying, and polymer
  • surprisingly, microwave heating has only been
    implemented in organic synthesis since the
    mid-1980s.
  • Today, a large body of work on microwave-assisted
    synthesis exists in the published and patent
    literature.
  • Many review articles, several books and
    information on the world-wide-web already provide
    extensive coverage of the subject.

20
  • 1969 Carrying out chemical reactions using
    microwave energy J.W. Vanderhoff Dow Chemical
    Company US 3,432,413
  • 1986 The Use of Microwave Ovens for Rapid
    Organic Synthesis Gedye, R. N. et alTetrahedron
    Lett. 1986, 27, 279
  • 1986 Application of Commercial Microwave Ovens
    to Organic Synthesis Giguere, R. J. and
    Majetich, G. Tetrahedron Lett. 1986, 27, 4945

21
Energy Use in Conventional Chemical Processes
  • Heating
  • Stirring
  • Piping
  • Transporting
  • Cooling

22
Problem of Conventional Heating
  • You heat what you dont want to heat.
  • Solvents for reactions, apparatus heated up and
    cool it down.
  • Double energy penalty without any apparent
    benefit.

23
(No Transcript)
24
Energy Consumptions
Three ways to get the reaction done, but
different energy bills to pay
25
Microwaves
  • MW reactors operate at 2.45 GHz.
  • Electric field oscillates at 4.9 x 109 times/sec
    10oC/sec heating rate.

26
(No Transcript)
27
Electromagnetic Spectrum
Neas, E. Collins, M. Introduction to Microwave
Sample Preparation Theory and Practice, 1988, p.
8.
28
Schematic of a Microwave
E electric field H magnetic field l wavelength
(12.2 cm for 2450 MHz) c speed of light (300,000
km/s)
29
Microwaves Application in Heating Food
1946 Original patent (P. L. Spencer) 1947 First
commercial oven 1955 Home models 1967 Desktop
model 1975 U.S. sales exceed gas ranges 1976
60 of U.S. households have microwave ovens
30
Spectrum Electromagnetic
  • Electric field component
  • Responsible for dielectric heating
  • Dipolar polarization
  • Conduction
  • Magnetic field component

31
Microwaves Dipolar Rotation
  • Polar molecules have intermolecular forces which
    give any motion of the molecule some inertia.
  • Under a very high frequency electric field, the
    polar molecule will attempt to follow the field,
    but intermolecular inertia stops any significant
    motion before the field has reversed, and no net
    motion results.
  • If the frequency of field oscillation is very
    low, then the molecules will be polarized
    uniformly, and no random motion results.
  • In the intermediate case, the frequency of the
    field will be such that the molecules will be
    almost, but not quite, able to keep in phase with
    the field polarity.
  • In this case, the random motion resulting as
    molecules jostle to attempt in vain to follow the
    field provides strong agitation and intense
    heating of the sample.
  • At 2.45 GHz the field oscillates 4.9 x 109
    times/s which can lead to heating
  • rates of 10 C per second when powerful waves
    are used

32
MW Heating Mechanism
Continuous electric field
Alternating electric field Withhigh frequency
Noconstraint
  • Two mechanisms
  • Dipolar rotation / polarization
  • Ionic Conduction mechanism

33
Microwave Dielectric Heating Mechanisms
Conduction Mechanism
Dipolar Polarization Mechanism
Dipolar molecules try to align to an oscillating
field by rotation
Ions in solution will move by the applied
electric field
Mingos, D. M. P. et al., Chem. Soc. Rev. 1991,
20, 1 and 1998, 27, 213
34
Microwave vs Oil-bath Heating
J.-S. Schanche, Mol. Diversity 2003, 7,
293. www.personalchemistry.-com www.biotage.com.
35
Conventional Heating by Conduction
Conductive heat Heating by convection currents Slo
w and energy inefficient process
temperature on the outside surface is in excess
of the boiling point of liquid
36
Direct Heating by Microwave Irradiation
  • Solvent/reagent
  • absorbs MW energy
  • Vessel wall transparent to MW
  • Direct in-core heating
  • Instant on-off

Inverted temperature gradients!
37
Molecular Speeds
38
Molecular Speeds
39
Microwave Ovens
Cooking Food!
Cooking Chemistry ???
Household MW ovens
The Use of Microwave Ovens for Rapid Organic
Synthesis R. Gedye et al., Tetrahedron Lett.
1986, 27, 279.
40
Publications on MW-Assisted Organic Synthesis
7 Synthetic Journals J.Org.Chem.,Org.Lett.,Tetrah
edron Lett.,Tetrahedron, Synth.Commun., Synlett,
Synthesis All Journals (Full Text) Dedicated
instruments only (Anton Paar, Biotage, CEM,
Milestone, Prolabo)
41
(No Transcript)
42
Industrial /Chemical / Applications of Microwave
Heating
Food Processing Defrosting Drying / roasting
/ baking Pasteurization
Plasma Semiconductors Waste Remediation
Sewage treatment
Drying Industry Wood, fibers, textiles
Pharmaceuticals Brick / concrete walls
Analytical Chemistry Digestion Extraction
Ashing
Polymer Chemistry Rubber curing,
vulcanization Polymerization
Biochemistry / Pathology Protein hydrolysis
PCR, proteomics Tissue fixation
Histoprocessing
Ceramics/Materials Alumina sintering Welding,
smelting, gluing
Medical Diathermy, tumor detection Blood
warming Sterilization (Anthrax) Drying of
catheters
43
Books on Microwave- Assisted Synthesis
(ACS Professional Reference Book) H. M. Kingston,
S. J. Haswell (eds.)
Hayes, B. L., CEM Publishing, Matthews, NC, 2002
Microwaves in Organic and Medicinal
Chemistry Kappe, C. O. and Stadler, A. Wiley-VCH,
Weinheim, 2005, ISBN 3-527-31210-2 410 pages, ca
1000 references,
?? Fundamentals of Microwave Application ??
Alternative Laboratory Microwave Instruments ??
Chemistry Applications ?? Biochemistry
Applications ?? Laboratory Microwave Safety
44
Books on Microwave- Assisted Synthesis
Lidstöm, P. Tierney, J. P. (Eds.), Blackwell Scie
ntific, 2005
Loupy Andre (Ed.) Wiley-VCH, Weinheim, 2003,
ISBN 3-527-30514-9 523 pages, 2000 refs.
Book (2 volumes) Wiley-VCHA. Loupy edit Second
Edition (2006) 22 Chapters
45
Books on Microwave-Assisted Synthesis
Practical Microwave Synthesis for Organic
Chemists - Strategies, Instruments, and
Protocols  Edition - 2009, X, 310 Pages,
Hardcover, Monograph
Astra Zeneca Research Foundation Kavitha
Printers, Bangalore, India, 2002 azrefi_at_astrazenec
a.com
46
Microwave Ovens
47
Monomodal instrument
Piccoli volumi processabili - Onde Stazionarie
(Hot Spots) - Difficoltà nello Scale-up Alta
densità denergia
Images adapted from C.O. Kappe, A. Stadler
Microwaves in Organic and Medicinal Chemistry,
Wiley, 2005
48
Multimodal instrument
Alta densità denergia (maggior potenza
disponibile) Maggiori volumi processabili
(cavità a MW più grande) No Onde Stazionarie
(No Hot-spots) Semplice Scale-up - Volume
minimo processabile
49
Monomodal Vs. Multimodal
50
Monomodal Vs. Multimodal
51
Thermal Effects
  • More efficient energetic coupling of solvent with
    microwaves promotes higher rate of temperature
    increase
  • Inverted heat transfer, volumetric
  • Hot spots in monomode microwaves
  • Selective on properties of material (solvents,
    catalysts, reagents, intermediates, products,
    susceptors)

52
(No Transcript)
53
Recent Applications of Microwave- Assisted
Synthesis-MAOS
54
Hydrolysis of benzamide
R. Gedye, F. Smith, K. Westaway, H. Ali, L.
Baldisera, L. Laberge, J. Rousell, Tetrahedron
Lett. 1986, 27, 279282. R. J. Giguere, T. L.
Bray, S. M. Duncan, G. Majetich, Tetrahedron
Lett. 1986, 27, 49454958.
thermal 1 h, 90 yield (reflux) MW 10 min, 99
yield (sealed vessel)
The first reports on the use of microwave heating
to accelerate organic chemical transformations
(MAOS) were published by the groups of Richard
Gedye (and Raymond J. Giguere/George Majetich in
1986. In those early days, experiments were
typically carried out in sealed Teflon or glass
vessels in a domestic household microwave oven
without any temperature or pressure measurements.
The results were often violent explosions due to
the rapid uncontrolled heating of organic
solvents under closed-vessel conditions.
55
Solvent-free Reactions or Solid-Solid Reactions
  • No reaction proceeds without solvent
  • Aristotle

Green chemistry enabled advancement
Solventless syntheses
56
Solvent-free Organic Synthesis
  • Chemical Synthesis w i t h o u t t h e u s e o
    f solvents has developed
  • i n t o a p o w e r f u l
  • m e t h o d o l o g y a s i t reduces the
    amount of toxic waste produced and therefore
    becomes less harmful to the
  • e n v i r o n m e n t

57
Solvent-free Organic Synthesis
Best solvent is no solvent!
  • Clean and efficient synthesis
  • Economic and environmental impact
  • Fast reaction kinetics

58
Adolf von Baeyer
59
Synthesis of Indigo
60
  • Towards
  • benign
  • synthesis
  • with
  • remarkable
  • Versatility
  • G. W. V. Cave, C. L.
  • Raston, J. L. Scott
  • Chem.Commun.
  • 2001, 2159

61
Solid-State General Oxidation with with Urea H2O2
Complex
R. S. Varma and K. P. Naiker, Org. Letters, 1999,
1, 189.
62
Solvent-free Oxidative Preparation of
Heterocycles
Kumar, Chandra Sekhar, Dhillon, Rao, and
Varma,Green Chem., 2004, 6, 156-157.
63
Solvent-free Synthesis of ß-Keto Keto Sulfones
Ketones
Kumar, Sundaree, Rao and Varma,Tetrahedron
Letters, 2006, 47, 4197-4199.
64
Solvent-free Reduction
F. Toda et al. Angew. Chem. Int. Ed. Engl., 1989,
28, 320and Chem. Commun., 1989, 1245.
65
Carbon-Carbon Bond Formation
Toda, Tanada, Iwata, J. Org. Chem., 1989, 54,
3007.
66
Solventless Photo Coupling and Photo
Rearangements
Y. Ito, S. Endo, J. Am. Chem. Soc. 1997, 119,
5974.
Shin, Keating, Maribay, J. Am. Chem. Soc. 1996,
118, 7626.
67
Solvent - Free Condensation
Z. Gross, et al., Org. Letters, 1999, 1, 599.
68
Solid-State Preparation of Dumb-bell-shaped C120
Wang, Komatsu, Murata, Shiro, Nature 1997, 387,
583
69
Advantages of Solid Mineral Supports (Alumina,
Silica and Clay)
  • Good dispersion of active (reagent) site can lead
    to significant improvement of reactivitylarge
    surface area.
  • The constraints of the (molecular dimensions)
    pores and the characteristics of the surface
    adsorption can lead to useful improvement in
    reaction selectivity.
  • Solids are generally easier and safer to handle
    than liquids or gaseous reagents.
  • Inexpensive, recyclable and environmentally
    benign nature.

70
Solid-supported Solventless Reactions
  • Microwave irradiation of solventless reactions
    with inorganic mineral supports such as alumina,
    silica, or clays have resulted in faster
    reactions with higher yields with simplified
    separation.

R. S. Varma, Tetrahedron, 2002, 58, 1235. R. S.
Varma, Green Chem., 1999, 1, 43.
71
Supported Reactions Using Microwaves
E. Gutterrez, A. Loupy, G. Bram, E. Ruiz-Hitzky,
Tetrahedron Lett. 1989, 30, 945.
72
Microwave-Assisted Deacetylation on Alumina
Varma et al. J. Chem. Soc., Perkin Trans. 1, 999
(1993)
73
Deprotection of Benzyl Esters via Microwave
Thermolysis
A practical alternative to traditional catalytic
hydrogenation
Varma et al. Tetrahedron Lett., 34, 4603 (1993)
74
Solid State Deoximation with Ammonium
Persulfate-Silica gel Regeneration of Carbonyl
Compounds Using Microwaves
Varma, Meshram Tetrahedron Lett., 38, 5427 (1997)
75
Solid State Cleavage of Semicarbazones/Phenylhydra
zones with Amm. PersulfateClay using Microwave
and Ultrasonic Irradiation
Varma, Meshram Tetrahedron Lett., 38, 7973 (1997)
76
Solid Supported Solvent-free Oxidation under MW
Varma et al., Tetrahedron Lett., 1997, 38, 2043
and 7823
77
Solvent-free Reduction Using MW
Chemoselective reduction of trans-cinnamaldehyde
olefinic moiety remains intact and the aldehyde
functionality is reduced in a facile reaction.
Varma et al., Tetrahedron Lett., 1997, 38, 4337
78
Hydrodechlorination under continuous MW
Pillai, Sahle-Demessie, Varma Green Chemistry,
6, 295 (2004)
79
Synthesis of Heterocyclic Compounds
Varma et al. J. Chem. Soc. Perkin Trans 1, 4093
(1998) Varma, J. Heterocycl. Chem., 36, 1565
(1999)
80
Synthesis of Heterocyclic Compounds
81
Organometallic Reactions
82
Rearrangements
83
Rearrangements
84
INDOLIZINES
  • Heterocyclic systems, 10- p electronics
  • Structure of many naturals alkaloids (-)
    slaframine, (-) dendroprimine, indalozine,
    coniceine
  • Key intermediates in indolizidines,
    bisindolizines, ciclofans, ciclazines synthesis-
    biologic actives compounds

85
Why interest for indolizinic products
Strong fluorescent properties
luminiscent products
  • Potentially fluorescents marker
  • Potentially laserscintillaters
  • Strong inhibitors for lipid peroxydation
    (15-lipooxygenase inhibitors )
  • Biologic actives products
  • Ligands for estrogen receptors
  • Possible inhibitory activity for phospholipase A2
  • Calcium-entry blockers
  • Bioorg. Med. Chem. Lett., 16, 59, 2006
  • Tetrahedron, 61, 4643, 2005
  • Bioorg. Med. Chem., 10, 2905, 2002
  • J. Org. Chem., 69, 2332, 2004
  • Dyes and Pigments, 46, 23, 2000
  • J. of Luminiscence, 82, 155, 1999

86
Indolizines by irradiation with microwaves, in
MCR
U. Bora, A. Saikia, R. C. Boruah Organic Lett.,
5 (4), 435, 2003
Asymmetric indolizines, by irradiation with
microwaves, in MCR
A. Rotaru, I. Druta, T. Oeser, T. Muller Helv.
Chim. Acta, 88, 1798, 2005
87
Synthesis of new indolizines
  • 32 dipolar cycloaddition of symmetrical or
    non-symmetrical 4,4-bipyridinium-methyne-ylids
    with actives alkynes, symmetrical or
    non-symmetrical
  • I. Druta, R. Dinica, E. Bâcu, I. Humelnicu
    Tetrahedron, 54, 10811, 1998
  • R. Dinica, C. Pettinari Heterocycl. Comm.,
    07(4), 381, 2001
  • A. V. Rotaru, R. P. Danac, I. Druta J.
    Heterocyclic Chem., 41, 893, 2004
  • A. Rotaru, I. Druta, T. Oeser, T. Muller Helv.
    Chim. Acta, 88, 1798, 2005

88
Synthesis of new substituted pyridinium-indolizine
s
  • Indolizinic cycloadducts using like
    dipolarophile 4-nitro-phenyl propiolate

89
Indolizine synthesis in solid phase, under
microwaves
90
Monoindolizine synthesis in solid phase, under
microwaves
Reaction conditions and the yelds for synthesized
compounds (12a-d)
Comp. Solution Solution Solution Solid phase Solid phase Solid phase Microwaves Microwaves Microwaves
Comp. Time (min) T (C) h () Time (min) T (C) h () Time (min) T (C) h ()
12a 480 50 63 10 95 57 10 95 84
12b 480 50 61 10 95 50 10 95 77
12c 480 55 71 10 95 52 10 95 85
12d 480 60 53 10 95 47 10 95 71
  • B. Furdui, R. Dinica, I. Druta, M. Demeunynck
    Synthesis, 16, 2640, 2006

91
Benefits of MW-Assisted Reactions
  • Higher temperatures (superheating / sealed
    vessels)
  • ?? Faster reactions, higher yields, any solvent
    (bp)
  • ?? Absolute control over reaction parameters
  • ?? Selective heating/activation of catalysts,
    specific effects
  • ?? Energy efficient, rapid energy transfer
  • ?? Can do things that you can not do
    conventionally
  • ?? Automation / parallel synthesis combichem

92
MW-Assisted Solvent-free Three Component
Coupling Formation of Propargylamines
Ju, Li and Varma, QSAR Combinatorial Science,
2004, 23, 891
93
Solvent-free Synthesis of Ionic Liquids
Varma, Namboodiri, Chem. Commun., 2001,
643. Varma, Namboodiri, Pure Appl. Chem., 2001,
73, 1307. Namboodiri, Varma, Chem. Commun., 2002,
342.
94
MW Synthesis of Tetrahalideindate(III)-based IL
Kim and Varma. J. Org. Chem., 2005, 70, 7882.
95
PEG, a Biodegradable Solvent
  • ?? PEG has been applied in bioseparations.
  • ?? PEG is on the FDAs GRAS list, (compounds
    Generally
  • Recognized as Safe) and has been approved by the
    FDA for
  • Internal consumption.
  • ?? PEG is weakly, immunogenic, a factor which has
    enabled
  • the development of PEGprotein conjugates as
    drugs.
  • ?? Aqueous solutions of PEG are biocompatible and
    are
  • utilized in tissue culture media and for organ
    preservation.
  • ?? PEGs are nonvolatile
  • ?? PEG has low flammability
  • ?? PEG is biodegradable

J. Chen, S. K. Spear, J. G. Huddleston, R.D.
Rogers, Green Chem.. 2005, 7, 64.
96
Suzuki Cross-Coupling Reaction in PEG Accelerated
by Microwaves
V. Namboodiri, R. S. Varma Green Chemistry,
2001, 3, 146.
97
Advantages of Present Approach
  • PEG offers a convenient recyclable reaction
    medium
  • Good substitute for volatile organic solvents
  • The microwave heating offers a rapid and clean
    alternative at high solid concentration and
    reduces the reaction times from hours to minutes
  • The recyclability of the catalyst makes the
    reaction economically and potentially viable for
    commercial applications

98
(No Transcript)
99
Water as a cleaner solvent
  • Water is not a popular choice of solvent,
  • reactivity in heterogeneous aqueous media is
  • not very well understood
  • But It brings biochemistry and organic
  • chemistry closer together in the beneficial use
  • of water as the reaction medium, it is abundant,
  • inexpensive and clean.

100
Cu (I) Catalyzed Click Chemistry
P. Appukkuttan, W. Dehaen, V. V. Fokin, E. Van
der Eycken. Org. Lett. 2004, 6, 4223.
101
N-alkylation of Amines using Alkyl Halides
Ju, Y. Varma, R. S., Green Chem. 2004, 6,
219-221.
102
Aqueous N-alkylation of Amines using Microwave
Irradiation
Ju, Y. Varma, R. S., Green Chem. 2004, 6,
219-221.
103
Why Amines and Heterocycles ?
104
(No Transcript)
105
MW Synthesis of N-Aryl Azacycloalkanes
Ju Varma, Tetrahedron. Lett., 2005, 46,
6011. Ju Varma, J. Org. Chem., 2006, 71, 135.
106
Choice of Reaction Media
107
MW -assisted one-pot synthesis of triazoles
108
(No Transcript)
109
(No Transcript)
110
Designing a greener synthesis
  • Plan!
  • Maximize convergence
  • Consider using renewable starting materials
  • Avoid super toxic reagents
  • Strive for high atom economy
  • Use catalytic over stoichiometric
  • Avoid auxiliaries and protecting groups
  • Consider greener solvents
  • Minimize number of purifications

111
Take Aways
  • Green chemistry is not so far away from what we
    do everyday
  • High yields
  • Minimal number of steps
  • Minimize number of purifications
  • Green principles to keep in mind
  • Strive for atom economy
  • Consider the toxicity and necessity of reagents
    and solvents

112
Green Chemistry Opportunities
  • Conferences
  • Annual ACS Green Chemistry and Engineering
    Conference
  • Annual Gordon Conferenece, Green Chemistry
  • Funding
  • PRF green chemistry grants
  • NSF green chemistry grants
  • EPA funding

113
Conclusion
Green chemistry Not a solution to all
environmental problems But the most fundamental
approach to preventing pollution.
114
  • Today, a large body of work on microwave-assisted
    synthesis exists in the published and patent
    literature.
  • Many review articles, several books and
    information on the world-wide-web already provide
    extensive coverage of the subject.

115
Lead References
  • Lidström, P. Tierney, J.P. Wathey, B. Westman,
    J. Tetrahedron 2001, 57, 9225
  • Hayes, Brittany, L. Microwave Synthesis.
    Chemistry at the Speed of Light. North Carolina
    CEM Publishing, 2002.
  • Tierney, J.P., and P. Lidström, ed. Microwave
    Assisted Organic Synthesis. Oxford Blackwell
    Publishing Ltd, 2005.
  • de la Hoz, A. Diaz-Ortiz, A. Moreno, A. Chem.
    Soc. Rev. 2005, 34, 164.

116
Lead References reviews
  • A. Loupy, A. Petit, J. Hamelin, F. Texier-
    Boullet, P. Jacquault, D. Math_, Synthesis1998,
    12131234 R. S. Varma, Green Chem. 1999, 4355
    M. Kidawi, Pure Appl. Chem. 2001, 73, 147151 R.
    S. Varma, Pure Appl. Chem. 2001, 73, 193198 R.
    S. Varma, Tetrahedron 2002, 58, 12351255 R. S.
    Varma, Advances in Green Chemistry Chemical
    Syntheses Using Microwave Irradiation, Kavitha
    Printers, Bangalore, 2002. A. K. Bose, B. K.
    Banik, N. Lavlinskaia, M. Jayaraman, M. S.
    Manhas, Chemtech 1997, 27, 1824 A. K. Bose, M.
    S. Manhas, S. N. Ganguly, A. H. Sharma, B. K.
    Banik, Synthesis 2002, 15781591. C. R. Strauss,
    R. W. Trainor, Aust. J. Chem. 1995, 48,
    16651692 C. R. Strauss, Aust. J. Chem. 1999,
    52, 8396 C. R. Strauss,

117
References books
  • Microwaves in Combinatorial and High-Throughput
    Synthesis (Ed. C. O. Kappe), Kluwer, Dordrecht,
    2003 (a special issue of Mol. Diversity 2003, 7,
    pp 95307)
  • Stadler, C. O. Kappe, Microwave-Assisted Organic
    Synthesis (Eds. P. Lidstr_m, J. P. Tierney),
    Blackwell Publishing, Oxford, 2005 (Chapter 7).
  • Loupy (Ed.), Microwaves in Organic Synthesis,
    Wiley-VCH, Weinheim, 2002.
  • B. L. Hayes, Microwave Synthesis Chemistry at
    the Speed of Light, CEM Publishing, Matthews, NC,
    2002.
  • P. Lidstrom, J. P. Tierney (Eds.), Microwave-
    Assisted Organic Synthesis, Blackwell Publishing,
    Oxford, 2005.
  • For online resources on microwave-assisted
    organic synthesis (MAOS), see www.maos.net.

118
THANK
YOU
FOR YOUR ATTENTION!
118
About PowerShow.com